The present invention pertains to detection of fluids. Particularly, the invention pertains to a phased heater array structure, and more particularly to application of the structure as a sensor for the identification and quantification of fluid components. The term “fluid” may be used as a generic term that includes gases and liquids as species. For instance, air, gas, water and oil are fluids.
Aspects of structures and processes related to fluid analyzers may be disclosed in U.S. Pat. No. 6,393,894 B1, issued May 28, 2002, to Ulrich Bonne et al., and entitled “Gas Sensor with Phased Heaters for Increased Sensitivity,” which is incorporated herein by reference; U.S. Pat. No. 6,308,553 B1, issued Oct. 30, 2001, to Ulrich Bonne et al., and entitled “Self-Normalizing Flow Sensor and Method for the Same,” which is incorporated herein by reference; and U.S. Pat. No. 4,944,035, issued Jul. 24, 1990, to Roger L. Aagard et al., and entitled “Measurement of Thermal Conductivity and Specific Heat,” which is incorporated herein by reference.
Presently available gas composition analyzers may be selective and sensitive but lack the capability to identify the component(s) of a sample gas mixture with unknown components, besides being generally bulky and costly. The state-of-the-art combination analyzers GC-GC and GC-MS (gas chromatograph-mass spectrometer) approach the desirable combination of selectivity, sensitivity and smartness, yet are bulky, costly, slow and unsuitable for battery-powered applications. In GC-AED (gas chromatograph-atomic emission detector), the AED alone uses more than 100 watts, uses water cooling, has greater than 10 MHz microwave discharges and are costly.
The phased heater array sensor may have separate chips for the concentrator, the separator, as well as for an off-chip flow sensor. However, these may be integrated onto one chip and provide improvements in the structural integrity and temperature control while reducing power consumption. The next phased heater array sensor involved an addition of integratable, micro-discharge devices for detection, identification and quantification of analyte. However, short of the full integration of the FET switches and shift register(s) onto the chip, there still was a need to wire-bond, route, connect and route about 110 wires from a daughter-board to mother-board with its micro-processor-controlled FET switches, which caused bulk and labor cost. In addition, the phased heater array sensor analyzers and conventional GCs seem to lack flexibility to change preconcentration and separation capabilities on-line.
Detection, identification and analysis of very small amounts of fluids in a less costly and more efficient manner are desired. Liquid chromatography analyzers of the related art are not portable, consume much power, and are slow and rather costly. However, eighty percent of the samples that need analyzing are liquid (e.g., medical, pharma, food and water quality, drug testing and industrial), for which related-art analyzers would not be well suited, especially if the differential pressures get into the 50 pounds per square inch (psi) to 10,000 psi (˜3.5 to 700 bar) range.